This chapter presents the results on the effectiveness of the cognitive-behavioral treatment concept presented in ► Chaps. 5 , 6 , 7 , 8 , 9 , 10 , 11 , and 12 . The findings are based on a sample of patients with multiple persistent somatic symptoms who were treated in the Outpatient Clinic for Psychotherapy of the Johannes Gutenberg-University Mainz according to the treatment approach presented in this manual. In addition to the classic outcome measures on the intensity of somatic symptoms, changes are also reported in other patient characteristics—such as illness anxiety, body-related dysfunctional cognitions, illness behaviors, measures of general psychopathology (e.g., depressive and anxiety symptoms) and the patient’s impairment in everyday functioning. Finally, the patients’ satisfaction with the individual therapy treatment concept is described.